Performance Improvement of TCP with an Efficient Contention Window Control Mechanism (ECWC) in IEEE 802.11 Based Multi-hop Wireless Networks
For multi-hop wireless networks using IEEE 802.11 most TCP performance degradation results from hidden, exposed terminal problems and bandwidth waste caused by exponential backoff of retransmission timer due to node’s mobility, not from collisions. However, in normal DCF algorithm, a failed user increases its contention window (CW) exponentially, thus it reduces the success probability of exposed terminal nodes. That is, these problems will cause burst data transmissions frequently in a particular node which already was successful in packet transmission, because the probability of successful packet transmission rate would be increased. To solve these problems, in this paper, we propose an efficient contention window control (ECWC) scheme to increase TCP performance in wireless multi-hop network. The proposed ECWC scheme is suggested to reduce the hidden and exposed terminal problems of wireless multi-hop network. That is, the proposed scheme increases the number of backoff retransmissions to increase the successful probability rate of MAC transmission, and fixes the contention window at a predetermined value.
KeywordsMedium Access Control Packet Transmission Medium Access Control Protocol Contention Window Distribute Coordinate Function
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